ST. PETERSBURG, Fla. — Justin Hagenman spent most of the spring with the rare non-elbow or shoulder injury that prevented him from throwing.

Diagnosed with a rib fracture in spring training, the right-hander was shut down from throwing for 10 weeks.

“It was just a unique [injury],” Hagenman said Tuesday at Tropicana Field before the Mets fell to the Rays 6-2. “You kind of just have to wait for the bone to heal. It took a lot of time, which is probably the longest I have taken off from throwing.”

Hagenman will be inserted into the Mets rotation Wednesday, allowing extra rest for Christian Scott. It will provide Hagenman an opportunity to show he can potentially be part of the organizational pitching depth heading into next season.

Hagenman showed flashes last season, pitching to a 4.56 ERA in nine appearances for the team, mostly as a bulk reliever. He was given a major league contract before last season despite never having pitched above Triple-A.

Justin Hagenman, who is returning from a long-term rib injury, throws a pitch during spring training. Charles Wenzelberg / New York Post

In three appearances for Syracuse this season, the 29-year-old was pitching to a 2.89 ERA.

“He throws strikes — that is what he gives you,” interim manager Andy Green said. “He’s done that his entire career. He’s done that well.”

Dylan Ross, a right-handed reliever, was recalled from Syracuse.

The Mets didn’t need to make a corresponding move with rosters expanding on Sept. 1, but will have to shed a pitcher when Hagenman is added.

Green said Ross’s fastball velocity (which has approached 100 mph) and splitter are appealing.

“He’s somebody for a while that we thought has a chance to impact this level and we’ll see what opportunity lays out there in front of him right now,” Green said.

Kodai Senga has five saves in as many chances since assuming the closer’s role with Devin Williams sidelined.

Senga had appeared in 11 games since the trade deadline, pitching to a 1.74 ERA with 12 strikeouts over 10 ¹/₃ innings during that stretch.